content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.observable.internal.operators;
  
  import java.util.Arrays;
  import java.util.concurrent.atomic.*;
  
  import io.reactivex.common.*;
  import io.reactivex.common.exceptions.Exceptions;
  import io.reactivex.common.functions.Function;
  import io.reactivex.common.internal.disposables.DisposableHelper;
  import io.reactivex.common.internal.functions.ObjectHelper;
  import io.reactivex.common.internal.utils.AtomicThrowable;
  import io.reactivex.observable.*;
  import io.reactivex.observable.internal.disposables.EmptyDisposable;
  import io.reactivex.observable.internal.queues.SpscLinkedArrayQueue;
  
  public final class ObservableCombineLatest<T, R> extends Observable<R> {
      final ObservableSource<? extends T>[] sources;
      final Iterable<? extends ObservableSource<? extends T>> sourcesIterable;
      final Function<? super Object[], ? extends R> combiner;
      final int bufferSize;
      final boolean delayError;
  
      public ObservableCombineLatest(ObservableSource<? extends T>[] sources,
              Iterable<? extends ObservableSource<? extends T>> sourcesIterable,
              Function<? super Object[], ? extends R> combiner, int bufferSize,
              boolean delayError) {
          this.sources = sources;
          this.sourcesIterable = sourcesIterable;
          this.combiner = combiner;
          this.bufferSize = bufferSize;
          this.delayError = delayError;
      }
  
  
      @Override
      @SuppressWarnings("unchecked")
      public void subscribeActual(Observer<? super R> s) {
          ObservableSource<? extends T>[] sources = this.sources;
          int count = 0;
          if (sources == null) {
              sources = new Observable[8];
              for (ObservableSource<? extends T> p : sourcesIterable) {
                  if (count == sources.length) {
                      ObservableSource<? extends T>[] b = new ObservableSource[count + (count >> 2)];
                      System.arraycopy(sources, 0, b, 0, count);
                      sources = b;
                  }
                  sources[count++] = p;
              }
          } else {
              count = sources.length;
          }
  
          if (count == 0) {
              EmptyDisposable.complete(s);
              return;
          }
  
          LatestCoordinator<T, R> lc = new LatestCoordinator<T, R>(s, combiner, count, bufferSize, delayError);
          lc.subscribe(sources);
      }
  
      static final class LatestCoordinator<T, R> extends AtomicInteger implements Disposable {
  
          private static final long serialVersionUID = 8567835998786448817L;
          final Observer<? super R> actual;
          final Function<? super Object[], ? extends R> combiner;
          final CombinerObserver<T, R>[] observers;
          final T[] latest;
          final SpscLinkedArrayQueue<Object> queue;
          final boolean delayError;
  
          volatile boolean cancelled;
  
          volatile boolean done;
  
          final AtomicThrowable errors = new AtomicThrowable();
  
          int active;
          int complete;
  
          @SuppressWarnings("unchecked")
          LatestCoordinator(Observer<? super R> actual,
                  Function<? super Object[], ? extends R> combiner,
                  int count, int bufferSize, boolean delayError) {
              this.actual = actual;
              this.combiner = combiner;
              this.delayError = delayError;
              this.latest = (T[])new Object[count];
              this.observers = new CombinerObserver[count];
              this.queue = new SpscLinkedArrayQueue<Object>(bufferSize);
          }
  
          public void subscribe(ObservableSource<? extends T>[] sources) {
              Observer<T>[] as = observers;
              int len = as.length;
              for (int i = 0; i < len; i++) {
                  as[i] = new CombinerObserver<T, R>(this, i);
              }
              lazySet(0); // release array contents
              actual.onSubscribe(this);
              for (int i = 0; i < len; i++) {
                  if (done || cancelled) {
                      return;
                  }
                  sources[i].subscribe(as[i]);
              }
          }
  
          @Override
          public void dispose() {
              if (!cancelled) {
                  cancelled = true;
                  cancelSources();
                  if (getAndIncrement() == 0) {
                      clear(queue);
                  }
              }
          }
  
          @Override
          public boolean isDisposed() {
              return cancelled;
          }
  
          void cancel(SpscLinkedArrayQueue<?> q) {
              clear(q);
              cancelSources();
          }
  
          void cancelSources() {
              for (CombinerObserver<T, R> s : observers) {
                  s.dispose();
              }
          }
  
          void clear(SpscLinkedArrayQueue<?> q) {
              synchronized (this) {
                  Arrays.fill(latest, null);
              }
              q.clear();
          }
  
          void combine(T value, int index) {
              CombinerObserver<T, R> cs = observers[index];
  
              int a;
              int c;
              int len;
              boolean empty;
              boolean f;
              synchronized (this) {
                  if (cancelled) {
                      return;
                  }
                  len = latest.length;
                  T o = latest[index];
                  a = active;
                  if (o == null) {
                      active = ++a;
                  }
                  c = complete;
                  if (value == null) {
                      complete = ++c;
                  } else {
                      latest[index] = value;
                  }
                  f = a == len;
                  // see if either all sources completed
                  empty = c == len
                          || (value == null && o == null); // or this source completed without any value
                  if (!empty) {
                      if (value != null && f) {
                          queue.offer(cs, latest.clone());
                      } else
                      if (value == null && errors.get() != null) {
                          done = true; // if this source completed without a value
                      }
                  } else {
                      done = true;
                  }
              }
              if (!f && value != null) {
                  return;
              }
              drain();
          }
          void drain() {
              if (getAndIncrement() != 0) {
                  return;
              }
  
              final SpscLinkedArrayQueue<Object> q = queue;
              final Observer<? super R> a = actual;
              final boolean delayError = this.delayError;
  
              int missed = 1;
              for (;;) {
  
                  if (checkTerminated(done, q.isEmpty(), a, q, delayError)) {
                      return;
                  }
  
                  for (;;) {
  
                      boolean d = done;
                      @SuppressWarnings("unchecked")
                      CombinerObserver<T, R> cs = (CombinerObserver<T, R>)q.poll();
                      boolean empty = cs == null;
  
                      if (checkTerminated(d, empty, a, q, delayError)) {
                          return;
                      }
  
                      if (empty) {
                          break;
                      }
  
                      @SuppressWarnings("unchecked")
                      T[] array = (T[])q.poll();
  
                      R v;
                      try {
                          v = ObjectHelper.requireNonNull(combiner.apply(array), "The combiner returned a null");
                      } catch (Throwable ex) {
                          Exceptions.throwIfFatal(ex);
                          cancelled = true;
                          cancel(q);
                          a.onError(ex);
                          return;
                      }
  
                      a.onNext(v);
                  }
  
                  missed = addAndGet(-missed);
                  if (missed == 0) {
                      break;
                  }
              }
          }
  
  
          boolean checkTerminated(boolean d, boolean empty, Observer<?> a, SpscLinkedArrayQueue<?> q, boolean delayError) {
              if (cancelled) {
                  cancel(q);
                  return true;
              }
              if (d) {
                  if (delayError) {
                      if (empty) {
                          cancel(q);
                          Throwable e = errors.terminate();
                          if (e != null) {
                              a.onError(e);
                          } else {
                              a.onComplete();
                          }
                          return true;
                      }
                  } else {
                      Throwable e = errors.get();
                      if (e != null) {
                          cancel(q);
                          a.onError(errors.terminate());
                          return true;
                      } else
                      if (empty) {
                          clear(queue);
                          a.onComplete();
                          return true;
                      }
                  }
              }
              return false;
          }
  
          void onError(Throwable e) {
              if (!errors.addThrowable(e)) {
                  RxJavaCommonPlugins.onError(e);
              }
          }
      }
  
      static final class CombinerObserver<T, R> implements Observer<T> {
          final LatestCoordinator<T, R> parent;
          final int index;
  
          final AtomicReference<Disposable> s = new AtomicReference<Disposable>();
  
          CombinerObserver(LatestCoordinator<T, R> parent, int index) {
              this.parent = parent;
              this.index = index;
          }
  
          @Override
          public void onSubscribe(Disposable s) {
              DisposableHelper.setOnce(this.s, s);
          }
  
          @Override
          public void onNext(T t) {
              parent.combine(t, index);
          }
  
          @Override
          public void onError(Throwable t) {
              parent.onError(t);
              parent.combine(null, index);
          }
  
          @Override
          public void onComplete() {
              parent.combine(null, index);
          }
  
          public void dispose() {
              DisposableHelper.dispose(s);
          }
      }
  }
  